TOF (Time-Of-Flight)-type distance image sensors (distance sensors) are known. For example, in Patent Literatures 1 and 2, technologies for improving the transfer speed of distance image sensors are disclosed. In the sensors described in Patent Literatures 1 and 2, one pair of transfer electrodes used for transferring electric charge generated in an electric charge generation region to an electric charge collection region are arranged along predetermined one side of the electric charge generation region having a rectangular shape. In the electric charge generation region, the impurity concentration increases toward the predetermined one side, and inclination in the potential distribution is formed toward the predetermined one side. Accordingly, electric charge generated in the electric charge generation region can easily move toward the transmission electrodes.
For example, in Patent Literature 3, for a distance image sensor, a technology for suppressing crosstalk between transfer electrodes to which signals of mutually-differing phases are input is disclosed. In a sensor disclosed in Patent Literature 3, the transfer electrodes to which signals of mutually-differing phases are input are arranged so as to face each other across an electric charge generation region. In the electric charge generation region, an impurity region that is an insulating area is disposed between the transfer electrodes. Accordingly, only electric charge generated in a portion disposed on one side of the impurity region in the electric charge generation region moves toward the transfer electrode of one side, and only electric charge generated in a portion disposed on the other side of the impurity region in the electric charge generation region moves toward the transfer electrode of the other side.